More accurately, it is a mathematical way of drawing a line in the sand between 7 and 9.
They then stick the Grade 8 boundary at the half way point between the two.
The point is that it is used to discriminate the very top each year. So where the grade 9 boundary falls depends on the distribution of marks each year.
It's to differentiate the very best. Not everyone is going to get that. An 8 is still a top grade.
Yes. A few of laughed when these changes were released that you could predict people bitching about the grade 9 when their child is the 8 side of the 8/9 divide (but they'd be happy with an A* which included both). But they wouldn't be complaining if their child got the 9. 8s and 9s are really great marks.
What would the teachers say to a high achieving child next year ? Total pot luck between 7 and 9 - oh the difference between them is 10 marks?
You teach your class the material and stretch them as far as you can and not stress about grade boundaries.
It's not pot luck. It just required more than playing the exam game. I tell mine that if they are looking for a simple, step by step way to 'get a 9', they're not a grade 9 student.
You don't get a grade 9 by ticking things off a checklist and calculating where to pick up individual marks. You get a 9 by having an exceptional grounding in the subject across the whole spec and texts and by applying knowledge in a way that is original, critical and with flair with reference to the question.
I got some grade 9s this year from students who were targeted 6s. If the questions were different, maybe they'd have not had the same flair. But they had exceptional knowledge, liked the question and when I saw the question later, I knew it would suit them.